Many nitroaromatic organic chemical contaminants present in the environment are known to be highly resistant to degradation. Current research has demonstrated that their persistence in the environment may be overcome by initially subjecting these contaminants to reducing conditions. Once the nitro groups are reduced to amine groups, the organic contaminants are usually degraded easily, generally by aerobic microbial processes.
Degradation of organic contaminants in microbial ecosystems occurs by both enzymatic and non-enzymatic mechanisms. An example of a non-enzymatic mechanism is the reductive dechlorination of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) by an iron porphyrin redox system wherein the DDT is reacted with a reduced iron porphyrin such as hematin. Most enzymatic reactions involve whole microbial cells such as bacteria, fungi and algae. Enzymatic reactions are usually more specific than non-enzymatic reactions but their activity is destroyed by harsh conditions such as exposure to high temperatures.
Microbial activity can assist degradation of organic contaminants either directly by enzyme production, or indirectly, by maintaining the reducing conditions of the environment and thereby enhancing the inorganic and biochemical mechanisms.
This invention relates to commonly assigned inventions disclosed and claimed in U.S. patent application Ser. No. 126,343, filed Sep. 24, 1993, titled "Composition and Method for Dehalogenation and Degradation of Halogenated Organic Contaminants," U.S. Pat. No. 5,411,664, and U.S. patent application Ser. No. 08/385,009, filed Feb. 7, 1995, by the inventors herein.